In the semiconductor device fabrication processes, vacuum process chambers are widely used for conducting various chemical or physical processes. For instance, vacuum process chambers are widely used in deposition processes such as chemical vapor deposition or physical vapor deposition; in coating processes such as a spin coating process for a photoresist material or a spin-on-glass material; and various other fabrication processes. In any of the processes, a vacuum chamber may be constructed of an upper chamber and a lower chamber, or an upper chamber lid and a lower chamber lid. The structure is designed to facilitate the loading and unloading of a semiconductor substrate into or out of a process chamber. For instance, in one of the common constructions for a vacuum process chamber, the lower chamber lid can be moved up and down while the upper chamber lid stays stationary with a substrate platform positioned in a cavity formed between the lower chamber lid and the upper chamber lid. A robot arm is used for reaching into the chamber cavity for the loading and unloading of substrates. After a substrate is properly seated on the substrate platform, the platform moves into its process position and the lower chamber lid closes onto the upper chamber lid to effect a vacuum-tight seal.
In the vacuum process chamber discussed above, the upper chamber lid is frequently fixedly attached to a support frame for the operation of the chamber. Since the support frame for the upper chamber lid is not always perfectly centered in relation to the lower chamber lid, the upper and the lower chamber lids are frequently not perfectly aligned. This results in leakage in the vacuum chamber and specifically, leakage around the edges of the chamber. For instance, in a spin coating apparatus for a photoresist material, it has been observed that during the coating of an adhesion promoter layer prior to the coating of the photoresist material, the process produces wafer edge defects in an area of approximately 8.about.20 mm wide around the wafer edge. The defects are caused by a leakage in the vacuum process chamber when ambient air leaks into the chamber and cause defect formation around the edge of the wafer. Typical defects formed are film coating pattern shift and film lifting.
An illustration for a conventional mounting method for a vacuum process chamber is shown in FIG. 1. The vacuum process chamber 10 consists of an upper chamber 14 and a lower chamber 16 used for the processing of a wafer 20 contained in a vacuum cavity formed when the upper chamber 14 and the lower chamber 16 are tightly closed together. The upper chamber 14 is rigidly and fixedly mounted by a mounting means 18 to a support frame 12 for mating with the lower chamber 16. It should be noted that the apparatus 10 is shown in FIG. 1 for illustration purpose only and in a much simplified manner. Since the upper chamber 14, or the upper chamber lid is rigidly and fixedly mounted to the support frame 12 through mounting means 18, a perfect alignment of the upper chamber 14 to the lower chamber 16 when the lower chamber 16 is moved up to close on the upper chamber 14 is extremely difficult. The rigid connection provided between the upper chamber 14 and the support frame 12 does not allow any lateral movement of the upper chamber 14 during the closing step for the upper and lower chambers.
It is therefore an object of the present invention to provide an apparatus for sealingly engaging an upper chamber lid and a lower chamber lid of a vacuum process chamber together that does not have the drawbacks or shortcomings of the conventional mounting apparatus.
It is another object of the present invention to provide an apparatus for sealingly engaging an upper chamber lid and a lower chamber lid of a vacuum process chamber together that permits lateral movement of the upper chamber lid relative to the lower chamber lid.
It is a further object of the present invention to provide an apparatus for sealingly engaging an upper chamber lid and a lower chamber lid of a vacuum process chamber together by mounting the upper chamber lid to a support frame via an universal joint device.
It is another further object of the present invention to provide an apparatus for sealingly engaging an upper chamber lid and a lower chamber lid of a vacuum process chamber together by utilizing a universal joint between the upper chamber lid and a support frame the lid is mounted and a plurality of compressible springs mounted on the support frame for exerting downward pressure on the upper chamber lid.
It is still another object of the present invention to provide an apparatus for sealingly engaging an upper chamber lid and a lower chamber lid of a vacuum process chamber together by utilizing a universal joint for lateral movement of the upper chamber lid and four compressible springs for achieving vacuum-tight seal.
It is yet another object of the present invention to provide a vacuum process chamber that includes a sealing means disposed between an upper chamber lid and a support member which includes a universal joint for allowing 360.degree. movement of the lid and a plurality of compressible spring for effecting a seal between the upper chamber lid and a lower chamber lid.
It is still another further object of the present invention to provide a vacuum process chamber that utilizes a universal joint between an upper chamber lid and a support member for allowing lateral movement of the upper chamber lid and four compressible springs equally spaced from each other for exerting a downward pressure on the upper chamber lid effecting a vacuum-tight seal with a lower chamber lid.
It is yet another further object of the present invention to provide a method for sealingly engaging an upper chamber lid to a lower chamber lid forming a vacuum process chamber by attaching the upper chamber lid to a support frame via an universal joint and at least three compressible springs projected downwardly from the support member for exerting pressure on the upper chamber lid and effecting a vacuum-tight seal between the upper and lower chamber lids.